1. Field of the Invention
The present invention relates to water-in-oil type emulsified compositions, and further to cosmetics which contain such a water-in-oil type emulsified composition.
2. Discussion of the Background
A water-in-oil type emulsified cosmetic has an outer layer composed of an oil component. Therefore, while it has advantages that it protects the skin, imparts flexibility and the like, it has had problems that when it is stored at a high temperature, the system is destabilized to cause water droplet coalescence or phase separation, and when it is applied to the skin, a sticky feeling may be provided because the outer phase is an oil. It has been a matter of common knowledge that by incorporating a silicone oil at a high content, such a sticky feeling can be eliminated. However, emulsification of a silicone oil per se is extremely difficult, and various attempts to stabilize emulsification have been carried out in the past.
JP-A-2006-169130 and JP-A-2006-306868 disclose a water-in-oil type emulsified composition with a high silicone oil content containing a specific emulsifying agent in order to obtain a water-in-oil type emulsified composition which is excellent in a feeling of use. However, the emulsifying agent that can be used for preparing such a water-in-oil type emulsified composition is extremely limited, and it is necessary to incorporate also a surfactant therein at a high content, etc. Therefore, it could not necessarily be declared that this technique is a general-purpose technique.
Further, JP-A-61-129033 discloses a technique for stabilizing a water-in-oil type emulsified composition using a clay mineral obtained by a treatment with a quaternary ammonium salt. Further, JP-A-8-20529 discloses that an extremely stable water-in-oil type emulsified composition can be obtained when an N-long chain acyl acidic amino acid ester and an organic modified clay mineral obtained by a treatment with a quaternary ammonium salt are incorporated therein. However, there is no examples in which a silicone oil has been incorporated at a high content as an oil phase, and in the case where a silicone oil is incorporated at a high content, an emulsified composition cannot be obtained, etc. Therefore, it could not be declared that this technique is a technique that can be applied to a silicone oil.
On the other hand, Japanese Patent No. 3802288 discloses an N-long chain acyl neutral amino acid ester. However, although such an N-long chain acyl neutral amino acid ester is known as an oily material with a high safety, it has not been known at all in the past that the N-long chain acyl neutral amino acid ester has an emulsifying ability.
Thus, a water-in-oil type emulsified composition with a high silicone oil content which is excellent in emulsification stability and whose sticky feeling has been improved remains eagerly awaited.